1. Field of the Invention
The present invention relates to underwater connector arrangements, for example underwater connector arrangements which are operable to provide wide-bandwidth signal transfer between two underwater objects without necessarily requiring a physical connection between them. Moreover, the present invention also concerns methods of transferring wide-bandwidth signals via underwater connector arrangements.
2. Description of Related Art
There is an increasing trend for deploying technical apparatus within ocean environments, for example associated with offshore exploration and production associated with oil and gas, as well as renewable energy systems which generate electrical power from ocean waves, ocean streams and ocean temperature differentials (Ocean Thermal Energy Conversion). Depletion of oil and gas reserves in the Middle East, onshore in the USA and in the North Atlantic Ocean has resulted in oil and gas companies considering boring and extracting for oil and gas in polar regions of the Earth which are largely devoid of land and covered in ice sheets. Moreover, most favourable conditions for ocean wave energy production lie in high latitudes approaching polar regions. Such aforementioned environments are harsh and technical apparatus failure can be costly to address. Moreover, ocean salt water is highly corrosive and conductive, which creates difficulties when undersea connections are being made. So whilst direct physical connections between conductors is a straightforward way of connecting cables, they face particular challenges when used underwater, particularly when it is necessary to separate and reconnect them underwater multiple times since this can adversely affect sealing integrity and so risk water ingress. Physical connections can also be hard to align accurately and are more restrictive in their ability to accommodate tight bending.
Inductive transfer of power at connectors has been described in a published United Kingdom patent application no. GB 2 456 039 A (Rhodes & Hyland, “Multimode wireless communication system”, Wireless Fibre Systems Ltd.) wherein there is described a multimode system which operatively employs three mechanisms of light, radio and acoustic carriers in combination with a selection arrangement for selecting a most appropriate of the three carriers. The search report associated with this patent application identifies numerous earlier patent applications: GB 2297667A; EP1370014A2; EP0338765A2; WO 02/071657 A2; US Pub 2002/0067531; U.S. Pat. No. 5,081,543.
Longer range underwater communication using radio frequency (RF) signals has also been proposed—e.g. as set out in US 2009/0212969 which describes a system for communicating between a well-head assembly and an umbilical termination using RF signals.
Despite the proposals made to date, they have not achieved widespread commercial acceptance and the Applicant has recognised that there are some significant shortcomings associated with previous proposals. It is an aim of the present invention at least partially to address such shortcomings and to provide a commercially attractive underwater connector system.